BR112016027714B1 - COMPOSITION, TOOL, AND METHOD FOR IMPROVING THE MECHANICAL PROPERTIES OF ELASTOMERS FOR DOWNTOWN APPLICATIONS - Google Patents

Abstract

composition, tool, and method for improving the mechanical properties of elastomers for downhole applications. compositions and methods for improving the mechanical properties of elastomers for downhole sealing applications are provided. one embodiment is a composition comprising: a base elastomer; a healing agent; and a semicrystalline polymer. another embodiment is a tool comprising: at least one component comprising a vulcanized elastomer, wherein the vulcanized elastomer comprises a base elastomer, a curing agent and a semicrystalline polymer. another embodiment is a method comprising: mixing a base elastomer, a curing agent and a semicrystalline polymer to form a mixture; placing the mixture in a mould; and vulcanize the mixture.

Description

FUNDAMENTALS

[001] The present disclosure provides compositions and methods to improve the mechanical properties of elastomers for downhole applications.

[002] Elastomers are compounds that are commonly used to manufacture components in a variety of downhole tools and other oilfield products, including O-rings, gaskets and packer parts. In particular, elastomers are polymeric materials (ie molecules formed by long chains of monomeric units) that exhibit a degree of viscoelasticity. When subjected to mechanical forces, elastomers typically can deform, stretch, extrude, etc. These mechanical properties make many elastomers suitable for applications where flexibility is important or desirable to create a seal. For example, the portion of a packer that deforms to seal the wellbore when the packer is seated (known as the element) is typically an elastomer.

[003] Vulcanization is a chemical process to change the mechanical properties of elastomers. Although the specifics of the process may vary, the vulcanization process usually involves combining additives (known as curing agents) with the elastomer and heating the mixture until it reacts. This reaction forms additional crosslinks between the individual elastomer polymer chains. As a result of these crosslinks, a vulcanized elastomer is stronger and more rigid than an equivalent elastomer that has not been vulcanized. The vulcanization process can be used to adapt the mechanical properties of an elastomer to a desired application by increasing the strength and stiffness of the elastomer.

[004] However, vulcanized elastomers can still show drastic changes in mechanical properties with an increase in temperature. These changes can include, for example, an increase in modulus and a decrease in final elongation before rupture. Such changes could have detrimental effects on product performance. Decreased elongation at high temperatures can have a detrimental effect on packer element performance. On the other hand, materials with lower modulus at ambient conditions but higher modulus at elevated temperatures may suffer from higher compression seating, higher explosive decompression, higher extrusion tendencies, or installation damage in sealing applications using O- rings.

BRIEF DESCRIPTION OF THE DRAWINGS

These drawings illustrate certain aspects of some of the embodiments of the present disclosure and are not to be used to limit or define the claims.

[006] Figure 1 is a diagram showing a cross-sectional view of a well system illustrating the use of an exemplary packer assembly having components comprising compositions that incorporate the present disclosure.

[007] Figure 2 is an enlarged-scale cross-sectional view of an exemplary packer assembly having components comprising compositions that incorporate the present disclosure.

[008] Figure 3 is a partially cross-sectional view of an alternative embodiment of an exemplary packer assembly having components comprising compositions that incorporate the present disclosure.

[009] Figure 4 is a graph illustrating data relating to percentage retention of stress at break point at 212°F and 302°F (relative to 72°F) for various embodiments of the present disclosure.

[0010] Figure 5 is a graph illustrating other data relating to percentage retention of elongation at break point at 212°F and 302°F (relative to 72°F) for various embodiments of the present disclosure.

[0011] While modalities of this disclosure have been depicted, those modalities do not imply a limitation on the disclosure and no such limitation should be inferred. The matter disclosed is capable of considerable modifications, alterations and equivalents in form and function, as will occur to those versed in the pertinent art and having the benefit of this disclosure. The modalities described and represented in this disclosure are examples only and are not exhaustive of the scope of the disclosure.

DESCRIPTION OF MODALITIES

[0012] The present disclosure provides compositions and methods for improving the mechanical properties of elastomers for downhole applications. In particular, the present application provides elastomer compositions comprising both a base elastomer and a semi-crystalline polymer additive.

[0013] There may be several potential advantages to the methods and compositions of the present disclosure, only a few of which are alluded to in this document. Elastomers used for downhole applications are often subjected to elevated temperatures that reduce mechanical properties such as strength and stiffness. It has been found that the inclusion of certain semi-crystalline polymers as additives in elastomer compositions used for downhole applications can improve the degree of retention of mechanical properties at these elevated temperatures.

[0014] According to embodiments of the present disclosure, there is provided a composition comprising a base elastomer, a curing agent and a semi-crystalline polymer additive. In certain embodiments, the base elastomer provides the majority of the material's mass. In certain modalities, the healer aids in the vulcanization process. In certain embodiments, the presence of the semi-crystalline additive modifies the mechanical properties of the composition. In certain embodiments, the composition can optionally comprise additional fillers or additives.

[0015] Base elastomers that may be suitable for use in accordance with the present disclosure include any elastomer that is capable of being used to fabricate tool components for use in downhole applications. Examples of suitable base elastomers include, but are not limited to, nitrile butadiene (NBR) which is a copolymer of acrylonitrile and butadiene, carboxylated butadiene acrylonitrile (XNBR), hydrogenated butadiene acrylonitrile (HNBR) which is commonly referred to as a highly nitrile saturated (HSN), hydrogenated carboxylated butadiene acrylonitrile (XHNBR), carboxylated hydrogenated butadiene acrylonitrile (HXNBR), ethylene propylene (EPR), ethylene propylene diene (EPDM), tetrafluoroethylene and propylene (FEPM), fluorocarbon (FKM), perfluoroelastomer (FEKM) and the like. It is within the ability of one of skill in the art, with the benefit of this disclosure, to select a suitable base elastomer for use in embodiments of the present disclosure.

[0016] The selection of the elastomer depends on the type of application to which the elastomer will be subjected during the lifetime of the hydrocarbon production. For example, elastomer requirements for the exploration and drilling phase using mud pumps, cementing equipment and Measurement During Drilling devices may be different from those used in the testing and completion phase (using logging equipment, drilling equipment cannon and line packers and hangers) which may differ from those required during the production phase (using wellhead equipment, chokes and valves, preventer assemblies, flow management equipment, risers and pipelines and flow lines). Some of the properties of elastomers that can be selected for their suitability for a particular stage in wellbore operations include thermal stability, chemical resistance, extrusion resistance, explosive decompression (ie, release of permeated or dissolved gases from a portion of the elastomer upon rapid depressurization), compression setting (degree of permanent dimension loss upon pressurization and depressurization), hardness, tensile and tear strength, tension relaxation, stiffness, elongation under tension and final elongation at break, and resistance to abrasion. In most cases, these properties should be studied under wellbore conditions. Temperatures, pressures, chemical environments and other downhole conditions can set the parameters for selecting suitable elastomers. At extreme temperatures and pressures, the range of potentially suitable elastomers can become very limited and expensive (eg perfluoroelastomers).

[0017] A variety of healing agents may also be suitable for use in accordance with the present disclosure. Without limiting the present disclosure to any particular theory or mechanism, curing agents can react with the base elastomer during the vulcanization process and create crosslinks between the polymer chains of the base elastomer to form a three-dimensional crosslinked network structure. These chains add strength to the resulting vulcanized elastomers and prevent melting. Examples of suitable curing agents include, but are not limited to, organic peroxides, sulfur compounds and azo compounds. For purposes of this disclosure, the term "elastomers" generally refers to elastomers that are cured before use. In published literature, the term "rubber" is typically used to refer to a cured elastomer.

[0018] A variety of semi-crystalline polymers may be suitable for use in accordance with the present disclosure, provided the semi-crystalline polymer has both a crystalline zone and an amorphous zone. The crystallinity of semi-crystalline polymers can range from about 10% to about 80%, depending on the conditions and form in which the molten polymer is cooled and the presence of nucleation additives. Melting points of semicrystalline polymers can range from about 60°C to about 325°C and glass transition temperatures of semicrystalline polymers can range from about -80°C to about 100°C. Examples of suitable semi-crystalline polymers include, but are not limited to, polypropylene (PP) (or syndiotactic or isotactic forms), polyethylene (PE), polyamides (eg, nylon 12), maleic anhydride grafted polypropylene (eg, FUSABOND® P MD353D) and maleic anhydride grafted polyethylene (eg FUSABOND® E MX11OD), polyphenylene sulfide, crystalline polystyrene, polyether ketone (PEEK), polyether ketone, thermoplastic polyimides, polyesters and combinations or mixtures thereof.

[0019] The interaction between the base elastomer and the semicrystalline polymer determines the properties of the compositions taught by the present disclosure. The base elastomer is typically an amorphous material. It can be subject to high elongation and it can expand or contract to withstand an applied tension. However, as noted earlier, elastomer material properties can change at higher temperatures. The material properties of the elastomer change because it has more thermal energy at these higher temperatures and this increase in thermal energy allows the material to stretch more easily. This impacts both the modulus and strength of the material. For example, elongation at break point is reduced.

[0020] In contrast, the semicrystalline polymers used in the present disclosure have both amorphous and crystalline domains. Without limiting the disclosure to a particular mechanism or theory, the crystalline zones are made of highly packed polymer that does not deform or stretch as easily until the melting point is reached and acts as solid reinforcing additives below the melting point. These crystalline zones are not affected by heat to the same degree as the amorphous zones, so their presence allows a composition containing the semicrystalline polymer to retain more of its mechanical properties, even as the temperature increases. Specifically, the inclusion of the semi-crystalline polymer can allow the composition to retain a higher percentage of its strength, elongation, and stiffness at higher temperatures relative to its strength and stiffness at lower temperatures. However, when the application temperature exceeds the melting point of the semicrystalline polymer, the molten liquid phase now present in the elastomer matrix acts to enhance elongation and lower modulus at elevated temperatures, thereby reversing the effects of temperature on mechanical properties of the original elastomer containing no semi-crystalline polymer. Additionally, when the application temperature exceeds the melting point of the polymer, the molten semicrystalline polymer can compensate for the loss of elongation that the elastomer undergoes at elevated temperatures by increasing elongation. This is possible because a softer liquid phase dispersed in a solid elastomer matrix makes the entire composite behave like a relatively softer elastic material.

[0021] The base elastomer can be polar or non-polar. The polarity of the elastomer can be controlled by using polar monomers, eg acrylonitrile. In some embodiments, elastomer polarity can be increased by introducing polar groups, such as carboxylate groups, either into the polymer backbone or by grafting polar groups onto the elastomer. An example of such an elastomer containing carboxylate groups is carboxylated butadiene acrylonitrile rubber (XNBR) or hydrogenated carboxylated butadiene nitrile rubber (XHNBR). Likewise, the semi-crystalline polymer can be polar or non-polar. It is generally advantageous to use a polar semicrystalline polymer when the base elastomer is polar. In certain embodiments, the semicrystalline polymer backbone monomer unit is a polar molecule. In other embodiments, the semicrystalline polymer backbone unit can be modified with a polar group to make it more compatible with a polar-based elastomer. An example of a semicrystalline polymer that has been modified with a polar group is maleic anhydride grafted polypropylene. Examples of such materials are commercially available under the trade name FUSABOND® from DuPont. In one embodiment, magnesium oxide or zinc oxide is used in combination with semi-crystalline polymers.

[0022] Compositions according to the present disclosure, optionally, may include other compounds as well. In certain embodiments, the properties of elastomers can be modified to meet performance requirements by adding suitable additives. For example, carbon black, silica, fibers and other additives are added as reinforcing fillers to increase modulus, hardness and tensile strength. Other additives, such as zinc acrylate and zinc methacrylate, are added to peroxide-cured elastomers to modify the rate and state of cure and to effect graft reactions on the elastomer backbone to improve the mechanical properties of the elastomers. Other additives include processing aids, antioxidants and compatibilizers, and the like. Selection of the appropriate elastomer depends on the application temperature range, chemical environment, fluid pressures, and the mechanical assemblies in which the elastomers are present.

[0023] The compositions of the present disclosure can be manufactured by mixing together the above-described components. In certain embodiments, the semicrystalline polymer is combined with the base elastomer in a range of from about 10 to about 20 parts per hundred parts of base elastomer. However, in other embodiments, the semicrystalline polymer can be present at as low as 5 parts per hundred or as high as 25 parts per hundred. Also, in certain embodiments, the curing agent can be combined with the base elastomer in a range of from about 2 to about 15 parts per hundred parts of base elastomer. In other embodiments, the curing agent can be present in a range of from about 4 to about 8 parts per hundred. The amounts of curing agents added define the degree of crosslinking of the elastomer components and as a result affect the hardness and elastic modulus and degree of elongation. It is generally accepted that the higher the crosslinking, the higher the hardness and modulus and the lower the elongation.

[0024] When the component materials have been combined, they can be melt blended to produce a relatively homogeneous mixture. They are mixed at a temperature of about 70°C, although the mixing temperature will depend on the melting temperature of the component materials. However, it is important that the mixing temperature is kept below the vulcanization temperature to prevent the composition from prematurely curing. The composition is typically in a molten liquid state or highly softened under mixing conditions.

[0025] After the components have been mixed, the resulting mixture can be poured into a mold as desired. Size and shape are generally determined by the specification and requirements of the final product. For example, the molten composition can be poured into an annular mold if the composition is used to make an O-ring or a packing element. However, the composition of the present disclosure can be molded into substantially any shape or size.

[0026] The composition is then vulcanized or cured by heating the composition to a temperature higher than the vulcanization temperature, typically while still in the mold. This heating can cause the base elastomer to react with the curing agents, as discussed above, and form the crosslinks that provide the final product with its strength and durability. Typically, the composition is heated to about 175 °C for at least 20-30 minutes. After vulcanization is complete, the composition is cooled and the final product is removed from the mold.

[0027] As a result of this process, the semi-crystalline polymer is mixed with the vulcanized elastomer. It has been found that, for high temperature performance improvement, semi-crystalline polymers such as nylon may be useful in sealing applications, whereas polymers such as polyolefins or maleic anhydride grafted polyolefins may be suitable for sealing elements. packer. Materials with higher stress values at all strain values can be useful in sealing applications, while materials with lower stresses and higher elongations at higher temperatures can be useful in packer applications. Modification of non-polar polyolefin polymers with polar maleic anhydride groups significantly increased final elongations. Furthermore, the use of semi-crystalline polymers can be added to expensive elastomers, such as perfloroelastomers (eg KALREZ®), which are high-cost, high-performance elastomers to reduce material cost without significantly compromising performance.

[0028] Additionally, semi-crystalline polymers may generally be less sensitive to chemical attack than elastomers for several reasons. First, the solubility parameters of typical chemicals found in downhole operations are significantly different from those for semi-crystalline polymers. Second, penetration of chemicals into a crystalline matrix is much less than that into an elastomer matrix. For example, Solubility Parameters for relevant polymers are: Nylon, 13.5; Nitrile rubber, 8.1; Polyethylene, 8.0; Polypropylene, 7.9 and PTFE, 6.2 (units cal1/2cm-3/2). The most acceptable solvents for the butadiene-based rubber type of materials fall in the range of 7.8-9.2. For example, the solubility parameter for toluene is 8.9. Thus, toluene is expected to be a non-solvent for nylon and polyolefins. Therefore, it is likely that the chemical compatibility of the composites of the present disclosure will be better than for the base elastomer composition.

[0029] The compositions of the present disclosure can be used in a variety of downhole applications including, for example, manufacturing a component of power tools used in the downhole. In general, the compositions may be suitable for any component of a downhole tool that experiences stresses and deforms in response to those stresses. In certain embodiments, the composition can be used to make the packing member of a plug, packer, or similar tool. In other embodiments, the compositions can be used to make O-rings or gaskets. A person skilled in the art with the benefit of this disclosure would be able to select the proper composition for a particular tool based, among other factors, on the material characteristics of the composition and the design requirements of the tool and tool component. For example, as discussed in connection with the data below, materials with higher stress values at all strain values can be useful in sealing applications, whereas materials with lower stresses and higher elongations at higher temperatures high can be useful in packer applications.

[0030] In one embodiment, the compositions of the present disclosure can be used to manufacture components used in a packer assembly, such as the sealing member. In this embodiment, the packer assembly can be used to create a physical barrier by isolating different zones of an open wellbore from one another in the drilling process. The packer assembly can be inserted into the downhole in an unexpanded form, even positioned within the wellbore where insulation is required. The packer assembly (and sealing element) can then be mechanically expanded to contact a portion of the outer surface of the column at the downhole and a portion of the inner surface of the casing or wellbore wall. The expansion of the packer assembly can create a barrier between the downhole column and the inner casing or exposed wellbore wall. These barriers may be able to withstand high temperatures and pressures, allowing isolation of different zones in the well. In some examples, a retrievable packer assembly can be used where the packer assembly is introduced to the downhole and used to complete a task, but is then recovered by retracting the sealing element so that the packer can be retrieved from the wellbore.

[0031] The illustrative modality of Figure 1 shows a well system 10 in which such an exemplary packer system can be used. In system 10, a packer assembly 12 is used to provide a fluid and pressure barrier in an annular 14 formed between a tubular 16 and an inner wellbore surface 18. Although surface 18 is shown in Figure 1 as being formed into a inside a casing, liner or other type of tubular column 20 that is encased in cement 22, surface 18 may instead be formed on an inner wall of a formation 24 (e.g., in an unlined portion of the well), or it could be any other surface in the well. Packer assembly 12 includes a sealing element 26 that extends outwardly to sealably contact surface 18. In this embodiment, sealing element 26 is disposed on tubular 16.

[0032] In the illustrated example, the sealing member 26 can be made of a composition comprising a base elastomer, a curing agent and a semi-crystalline polymer additive. Furthermore, in this embodiment, the sealing element 26 is restricted from longitudinally displaced in the annular 14 by means of end rings 28 positioned at opposite ends of the sealing element 26.

[0033] With reference now additionally to Figure 2, a schematic cross-sectional view of packer assembly 12 is representatively shown removed from the remainder of well system 10. In this embodiment of packer assembly 12, end rings 28 are coupled to a tubular 16. In the downhole system 10, the tubular 16 can be provided with suitable threaded end connections (not shown) and can be coupled as a part of a downhole string (not shown). Packer assembly 12 may alternatively be used in other well systems without departing from the principles of disclosure.

[0034] Referring now to Figure 3, another embodiment of a well system 30 is shown. Packer assembly 32 is shown without longitudinally restrictive elements such as end rings 28 (shown in Figure 1). Packer assembly 32 is used to provide a fluid and pressure barrier in an annular 14 formed between a tubular downhole column 34 and an inner wellbore surface 18. Although surface 18 is shown in Figure 3 as being formed in an interior of a casing, liner or other type of tubular column 20 that is encased in cement 22, surface 18 may instead be formed on an inner wall of a formation 24 (e.g., in an unlined portion of the well), or it could be any other surface in the well. Packer assembly 12 includes a sealing element 26 which is extended outwardly to sealably contact surface 18. In this system 32, sealing element 36 is disposed directly on the tubular shaft 34.

[0035] A method of operating the exemplar packer set is also provided. The method may include the steps of providing a packer assembly comprising a tubular and at least one sealing element disposed on the tubular, wherein the sealing element comprises a vulcanized elastomer comprising a base elastomer, a curing agent and a curing additive. semi-crystalline polymer; positioning the packer assembly in at least a portion of a wellbore; and expanding the seal to contact the inner surface of a casing, liner or other type of tubular column that is encased in cement (the surface could instead be formed on an inner wall of a formation or it could be any other surface in the well) and the outer surface of the tubular. In certain embodiments, the method may further comprise recovering the packer assembly by allowing the sealing member to at least partially retract so that the packer assembly can be retrieved from the wellbore to the surface.

EXAMPLES

[0036] To facilitate a better understanding of the present disclosure, the following examples of certain aspects of some preferred embodiments are given. In no way should the following examples be read to limit or define the scope of the claims.

[0037] A series of experiments was carried out to test the effects of adding various semi-crystalline polymers to a base elastomer. The base elastomer tested for these experiments was hydrogenated nitrile butadiene rubber (HNBR). All samples contained 25% N55O carbon black, magnesium oxide (50 microns in size) for all but one compositions, and Sartomer Corporation SARET® S633 and SARET® S634 co-agents. Samples were cured with peroxide, VUL-CUP® 8100 (a,a'-bis (tert-butylperoxy) di-isopropylbenzene, available from Arkema Chemicals.

[0038] The vulcanized composite was prepared according to some modalities described herein using first melt mixing (chewing) followed by molding. The composite mixtures were melt blended first using a rubber blender supplied by Brabender. The mixing chamber of the rubber mixer was preheated to 70°C (158°F) and the screw rotation rate was set at 30 RPM. The rubber blender was loaded in the following order: elastomer, semi-crystalline polymer, reinforcing agent, magnesium oxide (when used) co-agents and vulcanizing agent according to the amounts shown in Table 1. The blend was blended into the rubber blender by 30 minutes at 30 RPM. The mixture was removed and cut into small pieces for molding into cubic prisms. To vulcanize and shape the mixture into sheets, the mixed mixture was loaded into the rectangular slit in a metal mold and vulcanized (cured) and compression molded at 177°C (350.6°F) for 20 minutes under a load of about 2000 to 3000 pounds. The sheet was stamped with dog bone molds to obtain samples for tensile testing. Hardness was measured by a Shore hardness tester and tensile strengths at different strains were measured by an Instrol tester supplied with a heating chamber.

[0039] Five semi-crystalline polymers were tested, including polypropylene (PP), polyethylene (PE), nylon 12, maleic anhydride grafted propylene (FUSABOND® P MD353D) and maleic anhydride grafted polyethylene (FUSABOND® E MX11OD). The purpose of the last two materials was to decrease incompatibility between the polar matrix polymer (HNBR) and the non-polar semicrystalline polyolefin polymer by incorporating polar groups into the non-polar polymers. The semicrystalline melting points were chosen in such a way that they melt around the temperature employed during mixing and recrystallize subsequent to vulcanization and curing. The melting points of polyethylene (low density), polypropylene and Nylon 12 are 110-120°C, 157-161°C and 178°C (Tg, 37°C), respectively. Melting points of maleic anhydride grafted PP and PE (low linear density) were 136°C and 122°C, respectively. The crystalline nature of the polymers was expected to increase the vulcanized composite modulus at temperatures below their melting points and possibly increase the ultimate elongation at temperatures below as well as above the melting point of the polymers. All semi-crystalline materials were added to ten parts per hundred parts base polymer (PHR). The compositions are listed in Table 1 below. Table 1

[0040] As shown in Table 2 below, various mechanical properties of the sample compositions were tested at room temperature (72°F). These properties included material hardness (Shore A) as well as tensile strength at various strains. The materials were stretched until they broke and stress was measured at intervals: 25% strain, 50% strain, 100% strain, 150% strain and 200% strain. Tensile stress at break point and elongation at break point were also measured. Table 2 - Mechanical Properties at 72° F

Tabela 4 - Propriedades Mecânicas a 302° F

[0041] The mechanical properties of the compositions were also tested at elevated temperatures. Samples of the compositions were heated to 212°F and 302°F. At each temperature, a sample was stretched until the sample ruptured. Tensile stress at break point and elongation at break point were measured. The results for 212°F and 302°F are shown in Table 3 and Table 4, respectively. Table 3 - Mechanical Properties at 212° F

Table 4 - Mechanical Properties at 302° F

[0042] As can be seen from the above data, heating the sample compositions lowered the mechanical properties to at least some degree, regardless of the presence or type of semi-crystalline material used. For example, as shown in Table 2, tensile stress at the 72°F control group break point is 4134 psi. As shown in Table 3, control group tensile stress at break point at 212°F is 1081 psi. As shown in Table 4, the control group tensile strength at breaking point at 302°F is 760 psi. All other samples also showed reduced mechanical properties (both tensile strength and elongation) at the breaking point when they were heated. However, the mechanical properties were reduced less when using a semi-crystalline material.

[0043] The data in Tables 2-4 were used to calculate the percentage retention of mechanical properties at 212°F and 302°F, and these percentages are shown in Table 5 below. For example, as discussed above, tensile stress at break point in the control group is 4134 psi at 72°F, 1,081 psi at 212°F, and 760 psi at 302°F. Thus, the control group retains 26% (ie, 1081/4134) of the tensile stress at the breaking point at 212°F and 18% (ie, 760/4134) of the tensile strength at the breaking point at 302°F. A similar calculation was made for the elongation at the breaking point. Table 5 shows the retention percentage for each of the high temperatures tested and each of the measured mechanical properties. Table 5 - Percentage Retention of Mechanical Properties at 212° F and 302° F

[0044] The percentage retention of mechanical properties is also shown in Figures 4 and 5. Figure 4 shows the percentage retention of stress at the breaking point. Figure 5 shows the percentage retention of elongation at break point. A comparison of the percent retention of mechanical properties at 212°F and 302°F for all systems tested indicates that the percent retention of ultimate stress at break (tensile strength) and ultimate elongation at break are increased when semi-crystalline polymers are incorporated into elastomer compositions.

[0045] The results also show that semi-crystalline polymers increased the Shore A hardness of the composites by about 4-7 units. Unmodified semi-crystalline polymers, except for nylon 12, lowered modulus and increased elongation at all temperatures. Nylon essentially maintained high modulus at all temperatures, while percentage elongations remained similar for the control sample at higher temperatures. Modification of non-polar polyolefin polymers with polar maleic anhydride groups significantly increased final elongations. Those materials with higher stress values at all strain values are expected to be useful in sealing applications, whereas materials with lower stresses and higher elongations at higher temperatures are expected to be useful in packer applications.

[0046] One embodiment of the present disclosure is a composition comprising: a base elastomer; a curative agent; and a semi-crystalline polymer. Optionally, the composition further comprises a filler selected from the group consisting of carbon black, silica, fibers and any combination thereof. Optionally, the base elastomer comprises an elastomer selected from the group consisting of nitrile butadiene, carboxylated butadiene acrylonitrile, hydrogenated butadiene acrylonitrile, hydrogenated carboxylated butadiene acrylonitrile, carboxylated hydrogenated butadiene acrylonitrile, ethylene tetrafluorene, propylene propylene, ethylene perfluoroelastomer and any combination thereof. Optionally, the curative agent comprises a compound selected from the group consisting of an organic peroxide, a sulfur compound, an azo compound and any combination thereof. Optionally, the semicrystalline polymer comprises a polymer selected from the group consisting of polypropylene, polyethylene, a polyamide, maleic anhydride grafted polypropylene, maleic anhydride grafted polyethylene, polyphenylene sulfide, crystalline polystyrene, polyether ketone, polyether ketone, a thermoplastic polyimide , a polyester and any combination thereof. Optionally, the semicrystalline polymer comprises at least one polar group. Optionally, the base elastomer and the semicrystalline polymer are both polar. Optionally, the semicrystalline polymer is present in an amount of from about 5 to about 25 parts per hundred of the base polymer.

[0047] Another embodiment of the present disclosure is a tool comprising: at least one component comprising a vulcanized elastomer, wherein the vulcanized elastomer comprises a base elastomer, a curative agent and a semi-crystalline polymer. Optionally, the vulcanized elastomer further comprising a filler selected from the group consisting of carbon black, silica, fibers and any combination thereof. Optionally, the semicrystalline polymer comprises a polymer selected from the group consisting of polypropylene, polyethylene, a polyamide, maleic anhydride grafted polypropylene, maleic anhydride grafted polyethylene, polyphenylene sulfide, crystalline polystyrene, polyether ketone, polyether ketone, a thermoplastic polyimide , a polyester and any combination thereof. Optionally, the semicrystalline polymer is present in the vulcanized elastomer in an amount from about 5 parts per hundred of the base polymer to about 25 parts per hundred of the base polymer.

[0048] Another embodiment of the present disclosure is a method comprising: mixing a base elastomer, a curative agent and a semi-crystalline polymer to form a blend; place the mixture in a mold; and vulcanize the mixture. Optionally, the mixture further comprises a filler selected from the group consisting of carbon black, silica, fibers and any combination thereof. Optionally, the base elastomer comprises an elastomer selected from the group consisting of nitrile butadiene, carboxylated butadiene acrylonitrile, hydrogenated butadiene acrylonitrile, hydrogenated carboxylated butadiene acrylonitrile, carboxylated hydrogenated butadiene acrylonitrile, ethylene tetrafluorene, propylene propylene, ethylene perfluoroelastomer and any combination thereof. Optionally, the curative agent comprises a compound selected from the group consisting of an organic peroxide, a sulfur compound, an azo compound and any combination thereof. Optionally, the semicrystalline polymer comprises a polymer selected from the group consisting of polypropylene, polyethylene, a polyamide, maleic anhydride grafted polypropylene, maleic anhydride grafted polyethylene, polyphenylene sulfide, crystalline polystyrene, polyether ketone, polyether ketone, a thermoplastic polyimide , a polyester and any combination thereof. Optionally, the semicrystalline polymer comprises at least one polar group. Optionally, the base elastomer and the semicrystalline polymer are both polar. Optionally, the semicrystalline polymer is present in an amount of from about 5 parts per hundred of the base polymer to about 25 parts per hundred of the base polymer.

[0049] Another embodiment of the present disclosure is a method comprising: providing a packer assembly comprising a tubular and at least one sealing element disposed on the tubular, wherein the sealing element comprises a vulcanized elastomer comprising a base elastomer, an agent curative and a semi-crystalline polymer additive; positioning the packer assembly in at least a portion of a wellbore; and expanding the seal to contact at least a portion of a wellbore; and expanding the seal to contact at least a portion of an inner surface of the wellbore or a casing disposed in the wellbore and at least a portion of an outer surface of the tubular. Optionally, the wellbore can comprise an unlined hole. Optionally, the method may further comprise allowing the sealing member to at least partially retract and/or retrieve the packer assembly from the wellbore to the surface.

[0050] Therefore, the present disclosure is well suited to achieve the aforementioned purposes and advantages, as well as those that are inherent thereto. The particular embodiments disclosed above are illustrative only, as the present disclosure may be modified and practiced in different, but equivalent, manners evident to those skilled in the art having the benefit of the teachings herein. Although numerous changes can be made by those skilled in the art, these changes are encompassed within the spirit of the object defined by the appended claims. Furthermore, no limitation is intended on the construction or design details shown here, other than as described in the claims below. Therefore, it is evident that the particular illustrative embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the present disclosure. In particular, the entire range of values (for example, "from about a to about b" or, equivalently, "from approximately a to b" or, equivalently, "from approximately aab") disclosed herein will be understood. as referring to the power set (the set of all subsets) of the respective value range. The terms in the claims have their clear, ordinary meaning, unless otherwise explicitly and clearly defined by the patent holder

Claims (16)

1. Composition to improve mechanical properties of elastomers for downhole applications, characterized by the fact that it comprises: a base elastomer; a curative agent; and a semicrystalline polymer, in which the base elastomer and the semicrystalline polymer are both polar. 2. Composition according to claim 1, characterized in that it further comprises a filler selected from the group consisting of: carbon black, silica, fibers and any combination thereof. 3. Composition according to claim 1, characterized in that the base elastomer comprises an elastomer selected from the group consisting of: butadiene nitrile, carboxylated butadiene acrylonitrile, hydrogenated butadiene acrylonitrile, hydrogenated carboxylated butadiene acrylonitrile, carboxylated butadiene acrylonitrile, carboxylated hydrogenated acrylonitrile ethylene propylene, ethylene propylene diene, tetrafluoroethylene, propylene, a fluorocarbon, perfluoroelastomer and any combination thereof. 4. Composition according to claim 1, characterized in that the curative agent comprises a compound selected from the group consisting of: an organic peroxide, a sulfur compound, an azo compound and any combination thereof. 5. Composition according to claim 1, characterized in that the semi-crystalline polymer comprises a polymer selected from the group consisting of: polypropylene, polyethylene, a polyamide, polypropylene grafted with maleic anhydride, polyethylene grafted with maleic anhydride, polyphenylene sulfide , crystalline polystyrene, polyether ketone, polyether ketone, a thermoplastic polyimide, a polyester and any combination thereof. 6. Composition according to claim 1, characterized in that the semi-crystalline polymer is present in an amount of 5 to 25 parts per hundred of the base polymer. 7. A tool for improving the mechanical properties of elastomers for downhole applications characterized in that it comprises at least one component comprising a vulcanized elastomer, wherein the vulcanized elastomer comprises a base elastomer, a curative agent and a semi-crystalline polymer, wherein the base elastomer and the semicrystalline polymer are both polar. 8. Tool according to claim 7, characterized in that the vulcanized elastomer further comprises a filler selected from the group consisting of: carbon black, silica, fibers and any combination thereof. 9. Tool according to claim 8, characterized in that the semi-crystalline polymer comprises a polymer selected from the group consisting of: polypropylene, polyethylene, a polyamide, polypropylene grafted with maleic anhydride, polyethylene grafted with maleic anhydride, polyphenylene sulfide , crystalline polystyrene, polyether ketone, polyether ketone, a thermoplastic polyimide, a polyester and any combination thereof. 10. Tool according to claim 7, characterized in that the semi-crystalline polymer is present in the vulcanized elastomer in an amount from 5 parts per hundred of the base polymer to 25 parts per hundred of the base polymer. 11. Method to improve mechanical properties of elastomers for downhole applications characterized by the fact that it comprises: mixing a base elastomer; a curative agent; and a semicrystalline polymer to form a blend, wherein the base elastomer and the semicrystalline polymer are both polar. place the mixture in a mold; and vulcanize the mixture. 12. Method according to claim 11, characterized in that the mixture further comprises a filler selected from the group consisting of: carbon black, silica, fibers and any combination thereof. 13. Method according to claim 11, characterized in that the base elastomer comprises an elastomer selected from the group consisting of: butadiene nitrile, carboxylated butadiene acrylonitrile, hydrogenated butadiene acrylonitrile, hydrogenated carboxylated butadiene acrylonitrile, carboxylated butadiene acrylonitrile, carboxylated hydrogenated acrylonitrile ethylene propylene, ethylene propylene diene, tetrafluoroethylene, propylene, a fluorocarbon, perfluoroelastomer and any combination thereof. 14. Method according to claim 11, characterized in that the curative agent comprises a compound selected from the group consisting of: an organic peroxide, a sulfur compound, an azo compound and any combination thereof. 15. Method according to claim 11, characterized in that the semicrystalline polymer comprises a polymer selected from the group consisting of: polypropylene, polyethylene, a polyamide, polypropylene grafted with maleic anhydride, polyethylene grafted with maleic anhydride, polyphenylene sulfide , crystalline polystyrene, polyether ketone, polyether ketone, a thermoplastic polyimide, a polyester and any combination thereof. 16. Method according to claim 11, characterized in that the semicrystalline polymer is present in an amount from 5 parts per hundred of the base polymer to 25 parts per hundred of the base polymer.